We are saved by grace through faith (Eph 2:8). Therefore, we must have faith. Moreover, the Lord wants us to have great and growing faith (see Mt 15:27ff). Consequently, we should pray: Lord, "increase our faith" (Lk 17:5) and "I believe; help my lack of faith" (Mk 9:24, our transl).
Jesus so much wants our faith to grow that he challenges us and may even shake our faith (Jn 6:61). To deepen our faith, He will use sickness, healing, death, miracles (see Acts 9:33-42), sorrows, joys, our vocations, work, etc. When Jesus comes again, will He find faith on this earth? (Lk 18:8) Jesus is doing everything possible to make sure that faith will be abounding when He returns.
Therefore, pray for greater faith. Learn and live God's word, for "faith comes through hearing, and hearing by God's word" (Rm 10:17, our transl). Finally, be willing to suffer for your faith. In this way your faith will deepen (see 1 Pt 1:6-7). What the world needs is men and women of great faith!